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Finding the Fourth Proportional to 611.40, 917.34 and 428.76

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Solution

The fourth proportional to 611.40, 917.34 and 428.76 is: 643.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    611.40 : 917.34 = 428.76 : x
  2. Step 2: Convert to fraction form
    611.40/917.34 = 428.76/x
  3. Step 3: Cross multiply
    611.40x = 917.34 × 428.76
  4. Step 4: Simplify right side
    611.40x = 393,318.70
  5. Step 5: Solve for x
    x = 393,318.70/611.40
  6. Step 6: Final answer
    x = 643.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.